Pyrotechnical device and process for extinguishing fires

ABSTRACT

A device and a method for explosive quenching of fires are indicated, for example forest and area fires. The quenching device contains two flexible hoses (1, 2) disposed next to one another and transversely to the direction of risk (5), and closable at both ends, for accommodating quenching agents, and in each case an explosive (3, 4) in or on the hoses (1, 2) atomizes the quenching agent by its ignition to form a mist, which is applied to the fire. In order to achieve a directed ejection of the quenching agent in the direction of the area of risk, the pulse (I 1 ) which emerges from the first hose (1) facing way from the area of risk is greater than the pulse (I2) emerging from the second hose (2) facing the area of risk. For differing hose diameters, dimensioning of the quantities of explosive in relation to the diameter of the associated hose is effected taking into account the density (of the quenching agent according to a formula according to the invention.

DESCRIPTION

The present invention relates to a device for explosive quenching offires, with two flexible hoses disposed next to one another andtransversely to the direction of danger, and closable at both ends, bothfilled with a first and a second quenching agent, and each with anexplosive material in or on the hoses, by means of ignition of which ineach case a pulse is generated and the quenching agent is atomised toform a mist and applied to the fire. The invention further relates to amethod of explosive quenching of fires with the device described.

Both such a device and such a method for explosive quenching of fires isfor example known from DE 195 00 477 C1. The principle of explosivequenching is based on the fact that during detonation of the explosivematerial within or in the vicinity of a homogeneous medium in the formof a quenching agent, an extremely high pressure is built up, so that,for example, a compressive shock runs through the water in the hose,which imparts to it an enormous impulse, atomizes it into the finestparticles and throws it from the center of the explosive chargesymmetrically into the environment. The advantage of atomization of apreferably aqueous quenching agent resides in the extremely highlyeffective quenching agent surface area in proportion to the quantity ofquenching agent used.

The disadvantages of the device and the corresponding method known fromDE 195 00 477 C1 reside in the unsatisfactory distribution of thequenching agent in the environment of the explosive hose upon detonationof the explosive charge. It has become apparent that when one singleexplosive hose is used, the quenching agent is distributed roughlyuniformly into one vertical lobe and one left-hand and one right-handhorizontal lobe, with practically no delivery of quenching agent takingplace at an angle of 45° to the ground surface. The delivery ofquenching agent at a 45° angle is, however, highly desirable in order toachieve an effective range and optimum surface coverage.

The utilisation of two explosive hoses disposed parallel next to oneanother has no effect on the disadvantage of an unsatisfactory spraycharacteristic at a 45° angle to the ground surface. Only the height andthe volume of the vertical lobe are considerably increased.

The present invention applies itself to this problem, the object ofwhich is seen to be further to develop both the already mentioned deviceknown from DE 195 00 477 C1 for explosive quenching of fires, andfurther to develop the corresponding method, so that a concentrateddelivery of quenching agent in the direction of danger is possible withsatisfactory penetration of space and surface coverage.

In achieving the set object, the device for explosive quenching of firesof the type already mentioned is designed according to the invention inthat the pulse from the first hose facing away from the direction ofrisk is at least twice as great as the pulse of the second hose facingthe direction of risk.

By the pulse of a body is known to be understood the product of its massand its velocity. Furthermore, the density identifies the ratio of themass of a body to its volume. Thus, the pulse imparted to the quenchingagent by the detonation is dependent on the volume and the density ofthe quenching agent and on the size of the explosive charge whichensures the velocity of the quenching agent particles. The alignment ofthe range of quenching agent towards the area of risk and the desiredejection characteristic is thus achieved in that the product of mass andvelocity of the quenching agent of the first explosive hose which, seenfrom the area of risk, lies behind the second explosive hose, imparts alarger pulse to the quenching agent in the second hose, than the latterhas obtained by its own explosive charge, resulting in a deviation ofthe main mass of the quenching agent into the direction of danger bymeans of superimposition of pulses.

The object underlying the invention is further achieved by a methodadapted to the device according to the invention, in which the essentialfactor is that the explosives of the first and of the second hose areignited simultaneously, in order to achieve the superimposition ofpulses described above.

Both the device according to the invention and the method have a seriesof advantages, which again considerably increase the efficiency duringexplosive quenching of fires. On the one hand there resides in anadvantage in the aimed ejection of the quenching agent itself, so that amore efficient utilisation of the quenching agent used can be achieved.In the known device and in the corresponding method, the quenching agentis emitted disadvantageously symmetrically to both sides of theexplosive hose or hoses, and in addition the horizontal lobes of thequenching agent are disposed in such a flat manner over the groundsurface that the efficiency of the use of quenching agent is extremelyunsatisfactory. In the embodiments according to the invention thequenching agent is emitted asymmetrically in the direction of the areaof risk and at an optimum angle to the ground surface, so that also anoptimum distribution and range of the quenching agent is achieved. As afurther advantage, by selection of one larger and one smaller explosivehose, the quantity of quenching agent not emitted in the direction ofthe area of risk is kept low.

Advantageous further developments of the device according to theinvention are given in claims 2 to 5, and of the method according to theinvention in claims 7 and 8.

Experimental tests have shown that the proportional number λ, whichindicates the proportion of the impulse I₁ of the first hose to theimpulse I₂ of the second hose and can be shown by the formula ##EQU1##(d=hose diameter, q=quantity of explosive, ρ=density of quenching agent)must be at least equal to 2 in order to achieve a satisfactorydirectional effect. To this extent, in a first further development ofthe device according to the invention, the pulse I₁ emitted by the firsthose is roughly twice as great as the pulse I₂ emitted from the secondhose. It has already been explained in the preceding that the pulseimparted to the quenching agent by detonation of the explosive chargewith respect to the present invention gives substantially a function ofthe diameter of the hose in which the quenching agent is accommodated,further the density of the quenching agent, and finally the size of theexplosive charge, expressed by the quantity of explosive q. As forexample explosive cords as preferably used at present, are obtainable inGermany only in commercially available sizes of 12, 20, 40 or 100 g/m,in order to optimize the use of quenching agent it becomes necessary toco-ordinate with one another the diameter of the hoses used, the size ofthe explosive charge and the type of quenching agent used. The quenchingagent for example can consist of pure water with the known density 1, orof a pre-foamed quenching agent with a substantially lower density.

Taking these factors into account, a further development of the devicefor explosive quenching of fires with a first explosive hose with afirst diameter and a first quenching agent with a first density, andwith a second explosive hose with a second diameter and a secondquenching agent with a second density brings about the desireddirectional characteristic of the ejection of quenching agent in thatthe quantity of explosive, the diameter and the density of the quenchingagent of the first hose facing away from the area of risk in relation tothe quantity of explosive, the diameter and the density of quenchingagent of the second hose facing the area of risk behave according to theformula ##EQU2##

As a result of this further development, the device according to theinvention permits any combinations of size of the two explosive hoseswith specific compositions of quenching agent, for which, according tothe formula given, a good approximation of the necessary quantities ofexplosive can be calculated. Otherwise expressed, when using explosivecords in commercially available discrete sizes, i.e. with apredetermined quantity of explosive, the corresponding hose diameterscan be determined taking into account the composition of the quenchingagent. Finally, it is possible with this further development to fill anexplosive hose with pre-foamed quenching agent instead of pure water, sothat the water requirement can be considerably reduced. This is of greatadvantage particularly in inaccessible places, for example in the caseof forest fires.

The second hose facing the area of risk preferably has a larger diameterthan that of the first hose facing away from the area of risk. Thebackground of this further development is that the second hose which islocated closer to the potential or existing seat of fire, functionspredominantly as a delivery system for quenching agent, while the other(first) hose substantially acts as a pulse emitter. It has also beenshown experimentally that it is sufficient if the second hose facing thearea of risk, which predominantly operates as a delivery system forquenching agent, is provided with a smaller explosive cord, whichsubstantially only has the purpose of bursting the second explosive hosesimultaneously with ignition of the explosive cord of the first hose.

To this extent, a further development of the invention provides that thequantity of explosive of the first hose is greater than the quantity ofexplosive of the second hose. In a particularly preferred way, the firstquenching agent in the first hose is water, and the second quenchingagent in the second hose is a mixture of water and a quenching additive,so that environmental stress and costs due to the quenching agentadditive can be kept as low as possible. The quenching additive can forexample be a pure foam former or a so-called "retarder". By a retarderis meant either salts, which penetrate into the pores of the burningmaterial and therefore prevent its exhalation, or thickening gels, whichare applied in the manner of a protective coating on the burningmaterial and thus smother the fire.

In further development of the method according to the invention,according to which the pulse emitted by the first hose must be greaterthan the pulse emitted from the second hose, it is once again providedthat the magnitude substantially determining the pulse, namely thequantity of explosive, the diameter and the density of the quenchingagent of the explosive hoses, are dimensioned according to thealready-mentioned formula ##EQU3## and that the explosives of the firstand of the second hose (1, 2) are ignited simultaneously.

In order to use the quenching device or to apply the method forpreventative fire protection on stationary installations, ignition ofthe explosive is preferably effected on the basis of a signal from adevice for early recognition of fire. In this case there are meant bythe term "stationary installations" for example oil or gas tanks,refineries, oil drilling or transporting installations, storage spaces,airport take-off and landing strips, or aircraft parking areas, withoutthis enumeration being exhaustive.

A device for early recognition of fire includes a sensor by means ofwhich the presence of a fire parameter such as smoke or the like isrecognised in the earliest stage of initiation of a fire, and leads totriggering off an alarm. In the following, two embodiments given by wayof example of the device according to the invention and thecorresponding method will be explained in more detail with reference toa drawing. Shown are:

FIG. 1: a schematic view of the explosive diagram with a single hoseaccording to prior art;

FIG. 2: a schematic view of the explosive diagram with two explosivehoses according to prior art lying next to one another;

FIG. 3: a schematic view of two explosive hoses in explanation of thefirst embodiment according to the invention;

FIG. 4: a schematic view of two hoses with differing diameters inexplanation of the second embodiment according to the invention; and

FIG. 5: a schematic view of the explosive diagram according to thesecond embodiment according to the invention.

FIGS. 1 and 2 show shematically the explosive diagrams during use of asingle explosive hose 1 and of two explosive hoses 1, 2 disposed inparallel next to one another according to prior art. A common factor inboth explosive diagrams is that the distribution of the quenching agentis symmetrical to both sides of the explosive hose or hoses. In eachcase a vertical lobe 6 and a left-hand horizontal lobe 7 and aright-hand horizontal lobe 8 are formed. The horizontal lobes 7, 8 arelocated flat above the ground 9.

It is clearly recognisable that in both explosive diagrams there is noemission of quenching agent at a 45° angle to the ground 9. The onlydifference between the explosive diagrams of FIGS. 1 and 2 resides inthe fact that the vertical lobe 6 when two explosive hoses 1, 2 are usedis considerably higher and of larger volume than when one single hoseaccording to FIG. 1 is used. The lack of ejection of quenching agent ata 45° angle to the ground 9, recognisable in the explosive diagrams, andthe low distribution of the horizontal lobes 7, 8 results in anefficient and unsatisfactory use of quenching agent. For a surfacecovering and wide ejection of quenching agent in the direction of danger5, deflection of the main mass of the quenching agent at an angle of 45°to the ground 9 is highly desirable.

FIG. 3 shows a schematic view of two identical explosive hoses 1, 2:disposed parallel and next to one another. The hoses are filled with aquenching agent closed at both ends. An explosive 3, 4 in the form of aflexible explosive cord is disposed in each hose 1, 2. The explosivecords are connected to a sensor and igniter device 10, by means of whichignition of the explosive charge is effected, so that the quenchingagent is atomized to form a mist and applied to the fire. In order toachieve a directed ejection of quenching agent upon detonation of theexplosive, in this first embodiment of the device according to theinvention, the quantity of explosive q1 of the first hose 1 facing awayfrom the area of risk is greater than the quantity of explosive q2 ofthe second hose 2 facing the area of risk (with reference to FIGS. 3 and4, the area of risk is on the right). Thus a larger impulse is emittedfrom the first hose than from the second hose, which leads to thedesired directional effect in the case of the superimposition of pulsescaused by the explosion of both hoses.

FIG. 4 shows a similar schematic view of two explosive hoses 1, 2 as inFIG. 3, in this case the explosive hose 1, in order to explain thesecond embodiment of the invention, having a smaller diameter than theexplosive hose 2. Further, the first hose 1 contains a first quenchingagent in the form of pure water, while the second hose contains a secondquenching agent in the form of a pre-foamed mixture of water and aquenching additive. Here also both hoses 1, 2 are each equipped with aflexible explosive cord 3, 4, which extends through the entire length ofthe explosive hoses 1, 2. In this embodiment of the device according tothe invention, i.e. in the case of explosive hoses with differingdiameters (d₁ ≢d₂), the quantity of explosive/q₁, the diameter d₁ andthe density of quenching agent ρ₁ of the first hose 1 facing away fromthe area of risk (on the right in FIG. 4) with respect to the quantityof explosive q₂, to the diameter d₂ and to the density of quenchingagent ρ₂ of the second hose facing the area of risk behave according tothe formula ##EQU4##

By means of this formula a good approximation of the ratios of explosivecharge/hose diameter/density of quenching agent can be calculated forthe use of two explosive hoses 1, 2 disposed parallel next to oneanother with the objective of achieving a directed ejection of thequenching agent upon detonation of the explosive. The followingapproximative values may be named as an example for the configuration ofthe explosive hoses 1, 2 according to the formula named above:

d₁ =14 cm;

q₁ =100 g/m;

d₂ =18 cm;

q₂ =12 g/m.

In the case of these exemplary values an ejection of quenching agentfocused on the area of risk is achieved, insofar as hose 1 is the onewhich is facing away from the area of risk and hose 2 is the one facingthe area of risk.

FIG. 5 shows a schematic view of an explosive diagram as achievable withthe second embodiment according to the invention. In this example thefirst hose 1 facing away from the area of risk has a smaller diameterthan the second hose 2 facing the area of risk. In accordance with theabove named formulae the hose 1 is however provided with a considerablylarger explosive charge for this purpose. The result in the explosivediagram is a greatly increased lobe 8 of quenching agent, directedtowards the right towards the direction of risk, which is generated by asuperimposition of pulses of the quenching agent thrown out from the twoexplosive hoses 1, 2. The lobe 8 of quenching agent is a mixture of thevertical lobe 6 and the pure horizontal lobe 8 according to FIG. 2 andthrows the main mass of the quenching agent to the right-hand sidetowards the direction of risk 5. In comparison therewith the left-handhorizontal lobe 7 has remained small, which likewise indicates anextremely directed and efficient use of quenching agent.

The method according to the invention will be explained again now withreference to FIG. 5.

The two flexible hoses 1, 2, closable at both ends, of which the hose 1has a first diameter d₁ and the second hose a second diameter d₂, arelaid out transversely to the direction of risk and parallel to oneanother in front of an area of risk, from which a risk of fire emergesin the direction of arrow 5. Then the hoses 1, 2 are each fitted with aflexible explosive cord 3, 4 and each filled with a quenching agent andclosed at the ends. The explosive cords 3, 4 are connected in a way notshown here to an igniter device. By means of detonating the explosivecords 3, 4 the quenching agents contained in the hoses 1, 2 are atomizedto form a mist and applied to the fire. By generating pulses ofdiffering sizes in both hoses 1, 2, a directed ejection of quenchingagent is achieved. In the explosive diagram shown in FIG. 5 the smallerhose 1 was fitted with a larger quantity of explosive than the largerhose 2. Finally, the explosive cords of the first and of the second hose1, 2 were simultaneously ignited, so that a superimposition of pulsesresulted.

What is claimed is:
 1. A device for explosive quenching of firescomprising a first flexible hose (1) and a second flexible hose (2)disposed next to one another and transversely to the direction of risk(5), wherein each hose is closable at both ends, filled, respectively,with a first and a second quenching agent, and each hose equipped withan explosive (3, 4) such that, by means of ignition of each explosive,respective first and second pulses (I₁, I₂) is generated, which atomizethe quenching agents to form a mist which is then applied to the fire,characterized in that the first pulse (I₁) which emerges from the firsthose (1) which faces away from the area of risk is at least twice asgreat as the second pulse (I₂) which emerges from the second hose (2)which faces the area of risk.
 2. The device according to claim 1,wherein said first flexible hose (1) has a first diameter (d₁) foraccommodating the first quenching agent, and wherein said secondflexible hose (2) has a second diameter (d₂) for accommodating thesecond quenching agent, characterised in that the quantity (q₁) ofexplosive (3), the diameter (d₁) and the density (ρ₁) of the quenchingagent of the first hose (1) are in relation to the quantity (q₂) ofexplosive (4), the diameter (d₂) and the density (ρ₂) of the quenchingagent of the second hose (2) according to the formula ##EQU5##
 3. Thedevice according to claim 1, characterized in that the diameter (d₂) ofthe second hose (2) is larger than the diameter (d₁) of the first hose(1).
 4. The device according to claim 1, characterized in that thequantity (q₁) of explosive (3) of the first hose (1) is greater than thequantity (q₂) of explosive (4) of the second hose (2).
 5. The deviceaccording to claim 1, chareterized in that the first quenching agent iswater and the second quenching agent is a water/retarder mixture.
 6. Thedevice according to claim 3, characterized in that the quantity (q₁) ofexplosive (3) of the first hose (1) is greater than the quantity (q₂) ofexplosive (4) of the second hose (2).
 7. The device according to claim3, charcterized in that the first quenching agent is water and thesecond quenching agent is a water/retarder mixture.
 8. The deviceaccording to claim 3, characterized in that the first quenching agent iswater and the second quenching agent is a water/foam mixture.
 9. Thedevice according to claim 2, characterized in that the second diameter(d₂) of the second hose (2) is larger than the first diameter (d₁) ofthe first hose (1).
 10. The device according to claim 2, characterizedin that the quantity (q₁) of explosive (3) of the first hose (1) isgreater than the quantity (q₂) of explosive (4) of the second hose (2).11. The device according to claim 2, charcterized in that the firstquenching agent is water and the second quenching agent is awater/retarder mixture.
 12. The device according to claim 2,characterized in that the first quenching agent is water and the secondquenching agent is a water/foam mixture.
 13. The device according toclaim 1, characterized in that the first quenching agent is water andthe second quenching agent is a water/foam mixture.
 14. A method forexplosive quenching of fires, comprising the steps of: laying out afirst flexible hose (1) and a second flexible hose (2) transversely tothe direction of risk in front of an area of risk, wherein said firsthose (1) has a first diameter (d₁) and said second hose (2) has a seconddiameter (d₂), wherein each hose is closable at both ends, and each hoseis equipped with a quantity (q₁, q₂) of explosive (3, 4) and each hoseis filled, respectively, with first and second quenching agents;ignitingthe explosives (3, 4) thereby generating, in each hose, respective firstand second pulses (I₁, I₂); atomizing the respective quenching agents bymeans of the respective first and second pulses (I₁, I₂) to form a mist;and applying the mist to the fire; characterized in that by means ofcorrespondingly dimensioning the quantity (q₁) of explosive (3), thefirst diameter (d₁) and the density of the first quenching agent (ρ₁) ofthe first hose (1) and the quantity (q₂) of explosive (4), the seconddiameter (d₂) and the density of the second quenching agent (ρ₂) of thesecond hose (2), the first pulse (I₁) generated in the first hose (1)facing away from the area of risk is greater than the second pulse (I₂)generated in the second hose (2) facing the area of risk, and in thatthe explosives of the first and of the second hoses (1, 2) are ignitedsimultaneously.
 15. The method according to claim 14, characterized inthat the quantity (q₁) of explosive (3), the first diameter (d₁) and thedensity (ρ₁) of the first quenching agent of the first hose (1) facingaway from the area of risk and the quantity (q₂) of explosive (4), thesecond diameter (d₂) and the density (ρ₂) of the second quenching agentof the second hose (2) facing the area of risk are dimensioned accordingto the formula ##EQU6## and in that the explosives of the first and ofthe second hoses (1, 2) are simultaneously ignited.
 16. The methodaccording to claim 14, serving for preventative fire protection onstationary installations, characterized in that ignition of theexplosives (3, 4) is effected on the basis of a signal from a device forearly fire detection.
 17. The method according to claim 15, serving forpreventative fire protection on stationary installations, characterizedin that ignition of the explosives (3, 4) is effected on the basis of asignal from a device for early fire detection.